The present invention relates generally to brushes, and more particularly, to dental appliances such as toothbrushes utilizing bristles.
Dental brushes, for uses such as dental hygiene, share common limitations related to the physical properties of their brush bristles. One limitation posed by the bristles is that they quickly start to wear. Users are often slow to replace their dental brushes since many times the evidence of wear is not discernible to an untrained eye until the amount of wear far exceeds operational limits for the dental brush. Remedying worn dental bristles of a toothbrush typically requires replacement of the entire dental brush, or at least the replaceable head portion which holds the bristles. Factors associated with replacement include the logistics of locating and purchasing a replacement and the expense of acquiring a suitable replacement.
Another limitation found with bristles for typical dental brushes regards their general hydrophilic nature. This hydrophilic nature encourages retention of moisture, which fosters growth of bacterial colonies on and near the bristles. Also, typical dental bristles further impose limitations including those regarding length, thickness, color, shape, clustering, frictional coefficient of bristle surfaces, surface hardness, abrasiveness, and patterning of the dental bristles on dental brushes, all that can hinder the effectiveness and the appeal of the dental brush.
Aspects of the invention are directed to a dental brush configured to aid with dental hygiene. The dental brush includes a shape memory alloy wire configured as a component of bristles having an austenitic transformation finishing temperature. The bristles have an original shape and are configured to return to their original shape for any amount of deformation of the bristles below a maximum deformation. In some embodiments, the shape memory alloy bristles are positioned a distance from one another. The distance is at least a minimum spacing. The amount of deformation for the maximum deformation is independent from the distance for the minimum spacing. In another embodiment, the shape memory alloy bristles are arranged in closely packed tufts in contact with other bristles of the tuft.
The dental brush further includes a dental brush head sized, shaped, and configured to receive the shape memory alloy bristles. The shape memory alloy bristles are affixed to the head in a pattern configuration. The pattern configuration includes affixation points where the shape memory alloy bristles are affixed to the dental brush head. The affixation points are positioned on the dental brush head such that the spacing between each pair of bristles is at least the minimum spacing. The pattern configuration further includes the height of each shape memory alloy bristle dependent upon its affixation point.
The dental brush also has a handle including a grip portion and a receiving end portion. The receiving end portion of the handle is coupled to the dental brush head. Other aspects of the invention include the shape memory alloy bristle being at least at least 50% Ni and at least 40% Ti. Further aspects include the shape memory alloy bristles further comprising a coating configured to cover the shape memory alloy wire. The coated shape memory alloy wire has a surface coefficient of friction smaller than that of the surface of the shape memory alloy wire without the coating.